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https://issues.apache.org/jira/browse/FLINK-5747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16085555#comment-16085555
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Sihua Zhou commented on FLINK-5747:
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Hi，[~StephanEwen], there's some problems i found with Eager Scheduling in flink
1.3.x. i will be preciate if you have time to review what i've posted in
(FLINK-7153)[link title|https://issues.apache.org/jira/browse/FLINK-7153], i
will close the issue if i was wrong.
Thanks.
Sihua zhou
> Eager Scheduling should deploy all Tasks together
> -------------------------------------------------
>
> Key: FLINK-5747
> URL: https://issues.apache.org/jira/browse/FLINK-5747
> Project: Flink
> Issue Type: Bug
> Components: JobManager
> Affects Versions: 1.2.0
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Fix For: 1.3.0
>
>
> Currently, eager scheduling immediately triggers the scheduling for all
> vertices and their subtasks in topological order.
> This has two problems:
> - This works only, as long as resource acquisition is "synchronous". With
> dynamic resource acquisition in FLIP-6, the resources are returned as Futures
> which may complete out of order. This results in out-of-order (not in
> topological order) scheduling of tasks which does not work for streaming.
> - Deploying some tasks that depend on other tasks before it is clear that
> the other tasks have resources as well leads to situations where many
> deploy/recovery cycles happen before enough resources are available to get
> the job running fully.
> For eager scheduling, we should allocate all resources in one chunk and then
> deploy once we know that all are available.
> As a follow-up, the same should be done per pipelined component in lazy batch
> scheduling as well. That way we get lazy scheduling across blocking
> boundaries, and bulk (gang) scheduling in pipelined subgroups.
> This also does not apply for efforts of fine grained recovery, where
> individual tasks request replacement resources.
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